Constructions are known which allow the rotatable interconnection of different elements and components, rotatable in relation to one another. One of the most widely known solutions is represented by the hinge joints interconnecting the sides of windows and doorleaves, generally consisting of a pivot and the interconnected part mounted so as to be rotated about the pivot. These types of mechanical hinges enable rotating, but only in one direction. U.S. Pat. No. 4,236,560 discloses a case or wallet consisting of a lid and a frame forming the casing proper, provided with a covering held in position in the frame by a double clamping action between the frame and an insert. The latter element is held in position by tongues or lugs bent out of a leg of the frame and bearing against the insert. Thus, a clamping action along the edge of the covering is accomplished along two lines extending substantially parallel to each other around the entire edge of the covering. Naturally, the axis of rotation does not change in this case. Mechanical hinges allowing bidirectional rotation have been also developed, such as the so-called Bommerhinges used on swing-doors, rigidly formed on places of rotation.
Hinges without pivots are also known. For example, so-called bend-hinges are mostly used for interconnecting the elements of folding screens, wallets or illusionists, etc. The common characteristic of such solutions lies in the fact that the hinges are fixed to the elements displacing in relation to each other; such hinges do, however, simultaneously enable a multiaxial displacement, in the form of a rotary motion. The hinges are parallel and run perpendicular to the axis of rotation. The hinges are flexible elastic straps, made of leather or textile, etc.
U.S. Pat. No. 4,162,648 disclosed an apparatus having a form removably receivable in a carton or the like to maintain the carton in a rigidly erect condition. A frame having side portions bounds an internal receptacle dimensioned to receive the carton in removably fitted relation therein, and side portions having corresponding edges delineate a line along which the carton is severed to convert the carton to a preselected configuration. In this case the folding is performed along the predetermined edges, and such folding cannot be repeated or changed.
German Pat. No. DE-AS 22 56 452 disclosed a looping and clamping device, used for lifting or holding loads. This device consists of a closed endless strap, connected to relatively less flexible straps. At the ends of the device, means ensuring a releasable connection are arranged. Strap-loops pass across the surface of the objects, but such straps are not fixed thereto.
Different recreational objects are also known in which folding plays an important role. Such a puzzle is disclosed, for example, in U.S. Pat. No. 3,892,411. The puzzle consists of a plurality of pivotal transparent strip members with indicia thereon. The strips are arranged around the edges of a square playing surface and are deployable in a preselected order to achieve a solution in an overlapped relationship such that the respective indicia are disposed in an alternating sequence.
U.S. Pat. No. 4,429,878 discloses a foldable puzzle card comprising four elongated rectangular strips, each including four equal card boards foldably connected with each other. The four strips are disposed to form a rectangular frame, and means are provided for foldably connecting a card board on both sides of one strip with end card boards on both sides of the other two strips. The strips are arranged perpendicularly to cause interconnected end card boards to overlap each other. Front and rear surfaces of each card board are provided with predetermined patterns so that suitable folding of the strips forms a desired pattern.